/* ============================================================
   Season ink background — scroll-driven progression
   Added 2026-10-25. Used by index.html / index-de.html / index-zh.html
   ============================================================ */

#season-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  overflow: hidden;
  pointer-events: none;
  background: #f4f1ea;
}

#season-bg .sb-layer {
  position: absolute;
  inset: -3%;
  background-position: center center;
  background-size: cover;
  background-repeat: no-repeat;
  opacity: 0;
  transform: scale(1.06);
  transition: opacity .6s cubic-bezier(.33, 0, .2, 1);
  will-change: opacity, transform;
  -webkit-mask-image: radial-gradient(120% 110% at 50% 46%, #000 34%, rgba(0,0,0,.9) 58%, rgba(0,0,0,.45) 82%, transparent 100%);
          mask-image: radial-gradient(120% 110% at 50% 46%, #000 34%, rgba(0,0,0,.9) 58%, rgba(0,0,0,.45) 82%, transparent 100%);
}

#season-bg .sb-veil {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(78% 62% at 50% 44%, rgba(250,248,244,.30) 0%, rgba(250,248,244,.50) 55%, rgba(250,248,244,.70) 100%),
    linear-gradient(180deg, rgba(250,248,244,.55) 0%, rgba(250,248,244,.16) 18%, rgba(250,248,244,.10) 68%, rgba(250,248,244,.40) 100%);
}

#season-bg .sb-particles {
  position: absolute;
  inset: 0;
  overflow: hidden;
}

#season-bg .sb-particle {
  position: absolute;
  top: -10vh;
  border-radius: 50%;
  opacity: .32;
  filter: blur(.4px);
  animation-name: sbDrift;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

@keyframes sbDrift {
  0%   { transform: translate3d(0, -12vh, 0) rotate(0deg); }
  100% { transform: translate3d(var(--sb-dx, 14px), 112vh, 0) rotate(320deg); }
}

/* Seal (印章) */
.season-seal {
  position: fixed;
  right: 20px;
  bottom: 20px;
  width: 46px;
  height: 46px;
  z-index: 30;
  display: grid;
  place-items: center;
  border-radius: 6px;
  background: #a8342a;
  color: #fdf3e7;
  font-size: 26px;
  line-height: 1;
  font-family: "Songti SC", "STSong", "Noto Serif SC", "Source Han Serif SC", "SimSun", serif;
  box-shadow: 0 4px 14px rgba(60,30,20,.28),
              inset 0 0 0 2px rgba(253,243,231,.55),
              inset 0 0 0 4px rgba(168,52,42,.95);
  transform: rotate(-3deg);
  opacity: .94;
  transition: transform .5s ease, opacity .5s ease;
  user-select: none;
}

.season-seal.is-changing {
  transform: rotate(-9deg) scale(.94);
  opacity: .7;
}

/* Legibility over the paintings */
.hero-title,
.hero-subtitle,
.hero-eyebrow,
.season-name,
.season-months,
.section-divider-label {
  text-shadow: 0 1px 16px rgba(250,248,244,.9), 0 0 44px rgba(250,248,244,.65);
}

.intro p {
  background: rgba(250,248,244,.62);
  padding: 1.5rem 1.6rem;
  border-radius: 6px;
}

@media (max-width: 600px) {
  .season-seal {
    width: 40px;
    height: 40px;
    font-size: 22px;
    right: 14px;
    bottom: 14px;
  }
  .intro p { padding: 1.1rem 1rem; }
}

@media (prefers-reduced-motion: reduce) {
  #season-bg .sb-layer { transition: none; }
  #season-bg .sb-particles { display: none; }
  .season-seal { transition: none; }
}